Adhesion shear strength test method for freshwater/seawater ice on carbon ceramic brake pads of amphibious aircraft

Purpose Based on the mechanical model of typical shear tests, this study aims to propose the test principle and method of freshwater/seawater ice adhesion shear strength of carbon ceramic brake pads for amphibious aircraft, designs and builds the test equipment, prepares the freshwater/seawater ice samples and completes the tests. Design/methodology/approach This study examines the influence of the icing process, mechanism, temperature and freshwater/seawater on ice adhesion shear strength of carbon ceramic brake pads and puts forward a test method for the freshwater/seawater ice adhesion shear strength of amphibious aircraft brake pads. Findings The obtained results examine the influence of the icing process, mechanism, temperature and freshwater/seawater on ice adhesion shear strength of carbon ceramic brake pads. The adhesion shear strength of frozen freshwater and of the seawater of Dalian, Qingdao, Fuzhou and Zhuhai on the surface of aircraft brake pads is measured at –10 to –50°C. It is found that the shear strength of freshwater increases first and then decreases with the decrease of temperature. The adhesion shear strength of seawater; however, increases mainly linear with the decrease of temperature. Originality/value The value of this paper is that the test method proposed and test results for the freshwater/seawater ice adhesion shear strength of amphibious aircraft brake pads provide technical support for the anti-icing design of amphibious aircraft brake devices.

ANALISIS DAYA DUKUNG TANAH TERHADAP KERUSAKAN JALAN DI DESA BULUTIGO KECAMATAN LAREN KABUPATEN LAMONGAN

Road damage in Bulutigo Village, Laren District, Lamongan Regency affects access to agricultural mobilization in Lamongan Regency. So the researchers studied the value of the carrying capacity of the soil that caused road damage on the Bulutigo Village road, Laren District, Lamongan Regency. This study also examines the factors that affect the decline in the value of the bearing capacity of the soil. Data processing shows that the road subgrade soil in Bulutigo Village, Laren District, Lamongan Regency has a low carrying capacity value in terms of water content testing with an average value of 16.66% which includes high water content, from the Atterberg limit, it is included in the class of clay soil type. has a high plastic value with a PI value of 34.61%. Meanwhile, in the CBR test, the CBR value was 6.80% which was included in the "enough" category. And in the direct shear strength test, the value of the internal shear angle () is 15.03o.

Redesign Geometri Lereng Penambangan Batugamping Kuari C di PT X Kecamatan Palimanan Kabupaten Cirebon Provinsi Jawa Barat

PT X is a cement producer which has a limestone mine in Palimanan District, Cirebon Regency, West Java Province. In the Quarry C limestone mining area there has been an landslide that has resulted in the inoperation of mining activities in the area. This research was conducted on the slopes of the Quarry C mine which had experienced a landslide. This study aims to determine the causes of landslides that occur, determine the value of cohesion, deep friction angles and safety factors when landslides occur, and recommend safe slope geometry with the input parameters results of back analysis. In this study, to determine the type of avalanche that occurs is done with stereographic projections that refer to the criteria of the landslide Hoek and Bray, 1981. Data taken in the form of strike and discontinuous dip fields using a geological compass. The initial parameter input uses physical property test data to obtain the value of natural density and mechanical properties testing, namely the shear strength test to obtain the value of cohesion and deep friction angle, as well as the compressive strength test to get the modulus young and poisson ratio values. To find out the value of cohesion, the friction angle in the safety factor during a landslide is performed back analysis using the probability method. Based on the results of data processing and data analysis conducted, it can be concluded that the landslides that occurred in section C1 to section C3 were in the form of arc slides. The results of back analysis of landslides in sections C1 through section C3 are in the form of cohesion and friction angle during landslides, namely for claystone lithology (c = 129.3 kPa, Ø = 25.04o) and for Marly Limestone lithology (c = 80.17 kPa, Ø = 11.23o). For the recommended slope geometry in section C1 is α = 8 o, H = 37.265 m with FK = 1,299 and section C2 is α = 10 o, H = 44.712 m with FK = 1,313. Abstrak. PT X adalah salah satu produsen semen yang mempunyai tambang batugamping di Kecamatan Palimanan, Kabupaten Cirebon, Provinsi Jawa Barat. Pada area penambangan batugamping Kuari C telah terjadi longsoran yang mengakibatkan tidak bisa beroperasinya kegiatan penambangan di area tersebut. Penelitian ini bertujuan untuk mengetahui penyebab kelongsoran yang terjadi, mengetahui nilai kohesi, sudut gesek dalam dan faktor keamanan saat terjadi longsor, serta merekomendasikan geometri lereng yang aman dengan input parameter hasil analisis balik. Pada penelitian ini, untuk mengetahui jenis longsoran yang terjadi dilakukan dengan proyeksi stereografi yang mengacu pada kriteria longsoran Hoek and Bray, 1981. Data yang diambil berupa strike dan dip bidang diskontinu menggunakan kompas geologi. Input parameter awal menggunakan data hasil pengujian sifat fisik untuk mendapatkan nilai natural density dan pengujian sifat mekanik yaitu uji kuat geser untuk mendapatkan nilai kohesi dan sudut gesek dalam, serta uji kuat tekan untuk mendapatkan nilai modulus young dan poisson ratio. Untuk mengetahui nilai kohesi, sudut gesek dalam faktor keamanan saat terjadi longsor dilakukan analisis balik dengan metode probabilitas. Berdasarkan hasil pengolahan data dan analisis data yang dilakukan, dapat disimpulkan bahwa longsoran yang terjadi pada section C1 sampai dengan section C3 berupa longsoran busur. Hasil analisis balik kelongsoran di section C1 sampai dengan section C3 berupa nilai kohesi dan sudut gesek dalam saat terjadi longsor, yaitu untuk litologi claystone (c = 129.3 kPa, Ø = 25.04o) dan untuk litologi Marly Limestone (c = 80.17 kPa, Ø = 11.23o). Untuk geometri lereng yang direkomendasikan pada section C1 adalah α = 8 o, H = 37.265 m dengan FK = 1,299 dan section C2 adalah α = 10 o, H = 44.712 m dengan FK = 1,313.

Effect of Water Storage on Hardness and Interfacial Strength of Resin Composite Luting Agents Bonded to Surface-Treated Monolithic Zirconia

Background: Durable bonding between resin composite luting agents (CLA) and zirconia is still a matter of controversy. The purpose of this study was to evaluate the effect of water storage on hardness and interfacial strength of three CLA, a non-adhesive (Multilink Automix/ML), an adhesive (Panavia F 2.0/PF) and a self-adhesive (PermaCem 2.0/PC), bonded to polished (CL) and grit-blasted (AL: 50 μm alumina, SJ: Sil-Jet + Monobond Plus silane) monolithic zirconia surfaces. Methods: CLA specimens (n = 5/cement, condition) were prepared, stored under dry conditions or immersed in water, and Vickers hardness (VH) measurements were obtained at 1 h, 24 h, 1 week and 3 weeks intervals. Optical profilometry was used to determine the roughness parameters (Sa, Sz, Sdr, Sci) of zirconia surfaces (n = 5/treatment). A shear strength test (SBS, n = 10 × 2/cement) was performed to assess the strength and fractography of the cements bonded to zirconia after isothermal water storage and thermal-cycling (TC). Results: PF demonstrated significantly lower VHN after water storage at all time intervals, PC at 1 w, 3 w and ML at 3 w. SJ and AL showed significantly higher values from CL in all roughness parameters. Weibull analysis revealed the following significance in σο ranking within the same material: AL, SJ, ALTC > SJTC, CL > CLTC (PF); SJ, SJTC, AL, ALTC > CL, CLTC (PC) and SJ, SJTC > AL > ALTC > CL, CLTC (ML). Within the same surface treatment subgroups, the significance in σo ranking was PC, ML > PF (before/after TC) for SJ; PC > PF > ML (before TC), PC, PF > ML (after TC) for AL, and PC > PF > ML (before/after TC) for CL. For the m ranking, the only significant difference within each material group was found in PC (AL > ALTC) and for the same surface treatment in AL (PC > ML). Conclusion: There are significant differences in the water plasticization susceptibility of the CLA tested; the materials with adhesive monomers were the most affected. Tribo-chemical silica coating combined with a silane coupling agent was the most efficient bonding treatment for the non-adhesive and the self-adhesive materials. The adhesive CLA performed better on alumina-blasted than on tribo-chemically coated surfaces.

Synthesis and characterization of polyurethane and its nanocomposite adhesive derived from biobased isocyanate and polyol

In the current research, the vegetable oil based polyurethane nanocomposite (PUNC) adhesive was prepared using transesterified castor oil (CO) based polyol, partially biobased aliphatic isocyanate (PBAI) and organically modified montmorillonite nanoclay (Closite 30B). The transesterified CO was synthesized by reacting CO with ethylene glycol, which was confirmed using proton nuclear magnetic resonance (1HNMR) analysis. Further, the prepared polyurethane (PU) and its nanocomposite adhesive with specific NCO: OH molar ratio 1.3:1 was confirmed by Fourier transform infrared spectroscopy (FTIR) analysis. The increasing of wt% of nanoclay loading level up to 3% into PU matrix increased the lap shear strength of the adhesive systems. Subsequently, the effect of polyurethane nanocomposite adhesives on the bonding strength of wood-to-wood and aluminum-to-aluminum substrate was studied using lap shear strength test. The nanoclay was observed to effectively intercalate into the polymer matrix. Moreover, the phase separation in PU and PUNC adhesive was studied using atomic force microscope (AFM) and differential scanning calorimetry (DSC) analysis.

Post-Earthquake Damage Assessment—Case Study of the Educational Building after the Zagreb Earthquake

In the wake of recent strong earthquakes in Croatia, there is a need for a detailed and more comprehensive post-earthquake damage assessment. Given that masonry structures are highly vulnerable to horizontal actions caused by earthquakes and a majority of the Croatian building stock is made of masonry, this field is particularly important for Croatia. In this paper, a complete assessment of an educational building in Zagreb Lower Town is reported. An extensive program of visual inspection and geometrical surveys has been planned and performed. Additionally, an in situ shear strength test is presented. After extensive fieldwork, collected data and results were input in 3Muri software for structural modeling. Moreover, a non-linear static (pushover) analysis was performed to individuate the possible failure mechanisms and to compare real-life damage to software results.

The improvement of the dynamic behavior of railway bridge transition zone using furnace slag reinforcement: A numerical and experimental study

Transition zones between railway tracks and bridge decks can cause higher dynamic impacts. A solution is smoothly changing the track stiffness by gradually mixing steel furnace slag into the stone ballast. A nominated bridge transition zone is divided into 5 blocks of 7 meters long, with the mixing percentages of 0%, 25%, 50%, 75% and 100%. The mechanical behaviors of furnace slag-ballast combinations (FS-BCs) were studied using experiments of shear strength test, Los Angles abrasion index and plate load test. Furthermore, the dynamic behavior of bridge transition zone with FS-BCs blocks was investigated using a field validated FEM model. Results show that the 100%, 75%, 50% and 25% furnace slag by weight of ballast can increase the shear strength and ballast layer bending modulus by 13%, 12%, 9% and 7% at speed of 300 km/h compared with those of the stone ballast. The FEM study shows that rail deflections are reduced about 20%, 14%, 21% and 16% at speed of 300 km/h corresponding to 100%, 75%, 50% and 25% FS-BCs and accelerations are significantly reduced as well as increasing FS content of each block in bridge transition zone so that a smooth bridge transition zone can be achieved.

Research on a Low Melting Point Al-Si-Cu (Ni) Filler Metal for 6063 Aluminum Alloy Brazing

A new type of low melting point Al-Si-Cu (Ni) filler metal for brazed 6063 aluminum alloy was designed, and the microstructure and properties of the filler metal were systematically studied. The results show that when the content of Cu in the Al-Si-Cu filler metal increased from 10 wt.% to 20 wt.%, the liquidus temperature of the filler metal decreased from 587.8 °C to 533.4 °C. Its microstructures were mainly composed of the α-Al phase, a primary Si phase, and a θ(Al2Cu) phase. After a proper amount of Ni was added to the Al-Si-20Cu filler metal, its melting range was narrowed, the spreading wettability was improved, and the microstructure was refined. Its microstructure mainly includes α-Al solid solution, Si particles, and θ(Al2Cu) and δ(Al3Ni2) intermetallic compounds. The results of the shear strength test indicate that the shear strength of the brazed joint with Al-6.5Si-20Cu-2.0Ni filler metal was 150.4 MPa, which was 28.32% higher than that of the brazed joint with Al-6.5Si-20Cu filler metal.

An effect of carboxymethyl starch addition on adhesion to paper of water-soluble pressure-sensitive adhesive

Introducing biopolymer derivative, i.e. carboxymethyl starch into pressure-sensitive adhesives for paper industry has been proposed. Obtained adhesives were transferred onto water-dispersible paper carrier giving repulpable double-sided splicing tape. The effect of carboxymethyl starch degree of substitution on essential adhesive properties: tack, peel adhesion, as well as shear strength for steel and various papers has been tested. Additionally, the solubility in water and alkaline medium has been evaluated. The highest tack and peel adhesion increase was reported for PSA containing CMS with degree of substitution DS 0.86, to fax paper. Moreover, the dynamic shear strength test imitating the shear conditions in paper processing revealed, that the highest values of this parameters exhibited the system with 15 wt.% CMS DS 0.86. For this system the shortest water-dissolving times as well as at elevated pH were noted: 314 s and 60 s, respectively.

Optimasi parameter resistance spot welding pada pengabungan baja electro-galvanized menggunakan metode Taguchi

The present study features analytical and experimental results of optimizing resistance spot welding performed using a pneumatic (electrode) force system (PFS). This optimization was carried out to incorporate the galvanized steel sheet material SECC-AF (JIS G 3313) and SPCC-SD (JIS 3141) sheet plate coated with zinc with a thickness of about 2.5 microns. The zinc coating on the metal surface causes its weldability to decrease. This study aims to obtain the highest tensile shear strength test results from the combination of the specified resistance spot welding parameters. The research method used the Taguchi method using four variables and a combination of experimental tingkats. This study's experimental tingkat is two tingkats in the first parameter and three tingkats in other parameters. Taguchi optimization results show that the highest tensile shear strength test obtained is 5049.64 N. This was achieved at 22 cycles of squeeze time, 25 kA of welding current, and 0,6-second welding-time, and 12 cycles of holding-time. The S / N ratio analysis found that the welding time had the most significant effect, followed by welding current, holding time, and squeeze time. The delta S / N ratio values were 0.62, 0,41, 0.34 and 0.07, respectively.